Filtering device



June 12, 1951 c. w. HELLBERG FI'LTERING DEVICE Filed July 22, 1946 INVENTOR. ZZflgeg Patented June 12, 1951 UNITED STATES PATENT OFFICE FILTERING DEVICE Carl W. Hellberg, Chicago, In. Application July 22, 1946, Serial No. 685,540

2 Claims. (01. 210-162) This invention relates to coffee makers of the so-called vacuum type, and particularly to the filtering devices used in such coffee makers.

In vacuum type coifee makers, the dry coffee, tea, or other ingredient is placed in an upper." bowl which communicates with a lower bowl in which the water is placed. Heat is applied to athe' lowerbowl .and the generated steam pressure forces the" heated liquid up through a suitable passageway and into the upper bowl to form,

cofi'ee orother infusion as the case may be. Heat 1 is withdrawn from the lower bowl, causin'gra condensation of the steamor vapor thereinfso that a partial vacuum is created. A filterin'g'device intermediate" the upper and lower bowls permits a retarded flow of liquid from the upper bowl to the lower bowl. The function of." the filtering device is to enable a clear liquid in-.

fusion to pass into the lower bowl while. preventing the passage of coffee grounds or-itea leaves.-- The strained liquid infusion thusv is drawn downwardly by reason of the partial -,vacuum in the lower bowl, leaving the residue in the,

upper bowl.

' Various difficulties have been encounteredheretofore in designing satisfactory filtering devices for usein coffee makers, and accordingly ityisf ened e gterior that is adapted to seat in the; upper bowl over the tube or other passageway leading to thejlower bowl of the coffee maker. The. roughened-portion of the filtering device, in conjunction with the inner surface of the upperbowl which it engages, acts as a strainer thereby preventing the solid contents from passing through with the .liquid. The filtering device also includes an elongated stem portion depending from the strainer portion thereof into the tubular passageway of the coffee maker. 1

An object of the invention is to provide a filtering device of the type just described having incorporated therein certain improvements which enable the device to be manufactured at low cost andyet afford various advantageous features.

It is a further object to provide a filtering-device of a novel construction whereby the strainer element and the stem portion are separable, thus affording individually replaceable partsand enabling the strainer element to be individually sized and shaped for greatest efiiciencywhilethe z remainder of the device, which does not require as great precision in its manufacture; can be turned out separately.

A still further object is to provide an improved filtering device in which the'strainer element can be reversed in its position relative to the stem and the filtering device as a whole can be reversed in position, yet continue tofunction satisfactorily.

Still another object'of the invention is to provide an improved filtering device that may be used in most vacuumhofiee makers now on the market employing agravity type filter and which will seat itself properly for filtering whether the coffee maker is tilted or the filtering device is inserted in a tilted position with respectto the coffee maker.

A still further object'is to increase the safety factor of a gravity type filtering device by'afford-' ing means of insuring that abnormal'pressures" built up in the lower bowl of the coffee maker are relieved.

It is a general object of the invention to provide an improved filtering device of simple design and construction which lends itself readily to inex-' pensive manufacture by simple and well known methods;

Various other objects, advantages and features" of the invention will be apparent from the following specification when taken in connection with the accompanying drawing wherein a p1"e' ferred embodiment is set forth for purposes of illustration.

In the drawing, wherein like reference numer-" als refer to like parts throughout:

Fig. 1 is an elevation-of a filtering device shown. in the position it normally occupies when in use; this device being constructed in accordance with and embodying the: principles of the invention;

Fig. 2 is a vertical sectional view taken on the line 22 in Fig. 1;

Fig. 3 is a detail view of the separable stem member of the filtering device, and

Figs. 4 and 5 are cross-sectional views taken on the lines 4-4 and 5-5, respectively, in Fig. 2.

Referring now to the drawing, and particularly to Figs. 1 and 2 thereof, there is shown a filteringdevice together with adjacent portions of the upper bowl or container of the coffee maker, the parts being shown in the positions normally" occupied when in use. In the illustrated embodiment the filtering device is composed of two parts, an elongated member II), also shown separately in Fig. 3, and a substantially spherical strainer element I2. These-parts may be made of any suitable, heat resisting material such as glass,

metal, plastic or vitreous material. The element I2 has a roughened exterior such as may be formed by stippling or serrating the surface thereof. A preferred manner of affording the roughened surface is to run criss-cross grooves or channels across the face of the element I2, thereby forming pyramidal projections or facets. The element I2 is adapted to seat in the lower part of the upper bowl I4 of the coffee maker, covering the tubular passageway I6 which leads down into the lower bowl or container of the coifee maker. Because of its roughened surface the strainer element I2 does not afford a tight seal where it engages the neck of the upper bowl The member III passes vertically through a suitable opening in the element I2, the lower portion or stem I8 of this member extending into the tube I6. The stem I8 serves as a guide in properly seating the filtering device and limits any tipping movement of the device relative to the bowl I 4. The member II] has an annularshoulder 20 which normally is disposed a slight distance below the element I2 and limits movement of the element I2 toward the stem I8. The

upper portion or stem 24 of the member ID facilitates insertion or removal of the filtering device. Longitudinal splines or keys 22 are formed on the stem 24 in spaced relation to the shoulder 20, and suitable keyways 26, Figs. 2 and 4, are provided in the element I2 communicating with the central opening therein so that the element I2 can slide over the stem 24 when the keys 22 and keyways 26 are aligned. After the parts of the filtering device are assembled, the element I2 is turned so that the keys 22 and keyways '25 are out of alignment, as indicated in Figs. 2 and 5. If desired, the angular separation between the keys 22 may be made less than 180 degrees so that the element I2 can slide over the stem 24 only when the parts are in a particular angularrelation to each other.

The element I2 is formed separately from the stem member .IU of the filtering device in the manufacture thereof. It is not essential that these two parts be made of the same material, althoughgenerally it may be found convenient to do so. The element I2 is accurately sized and shaped to seat in the upper bowl It in such a manner as to achieve the desired result of straining the liquid infusion as it is drawn from the upper bowl into the lower bowl of, the cofieei maker. The openings 26 in the element l2 are made sufficiently small to prevent the coffee grounds or the like from seeping intothe lower container. There is little tendency for the grounds to collect near the top of the element I2,- practically all of the residue accumulatin'g'in the neck of the bowl it surrounding the line of contact between the element I2 and bowl I4. The element I2 is made sufiiciently heavy so that it properly seats when liquid is being withdrawn from the upper bowl and yet may be unseated by the liquid when it rises through the tube IE to enter the upper bowl I4. Thus, it has a valve action which enables it to accommodate a rapid flow of liquid into the upper bowl and a gradual withdrawal of the liquid therefrom. The stem Iii, being lighter in weight than the filtering device as a whole, readily rises when the vapor pressure in the lower bowl exceeds a predetermined value. This feature is of value in the event the element I2 becomes clogged with coifee grounds or other residue and is unable to move from its seat in the upper bowl I4. Under such circumstances'the stem ID will have a piston-like action whereby the shoulder 21! strikes the element I2 to jar it loose. In this way the building up of an excessive steam pressure in the lower bowl is averted.

There has been shown and described a preferred form of filtering device for efficiently straining solids from liquid infusions in vacuum type coffee makers. It should be noted that the two-piece construction of the filtering device enables replacement of the member I B or element I2 individually in the event either of these parts isdamaged. This feature also enables the element I2 to be formed separately from the member I'll, which latter member does not require such high accuracy in its manufacture. The device "affords a ready escape for steam and expanded air under excessive pressure so that the danger of explosion due to the clo gin of the valve or strainer member I2 is eliminated. The element ill I2 may be turned upside down in position if desired;- thus affording two distinct filter faces thereon. In addition, the assembled unit may be placed in an upright or inverted position for filtering with equal efficiency. .The spherical configuration of the elementl'Z enables the filter device v.tooperate satisfactorily whether in .a strictly upright position or slightly tilted, as may occur when it is carelessly inserted; It willalso operate satisfactorily even though the upper bowl may be tilted away from'the vertical. The filter element !2 can be cleaned readily and is easily;v

removed from thestem' I0 for this purpose.-

It is obvious'that' various changes maybe'made:v in the specific embodiment set forth'for purposes:

of illustration without departing from the spiritof the invention. The invention is accordingly; not to be limited to the specific embodiment shown and described, but only as indicated in the following claims.

The invention is hereby claimed as follows:

1. A filtering device for a vacuum type infusion apparatus comprising a substantially sphericalstrainer element of unitar and integral construction having an outer roughened surface and a central axial opening therethrough, said axial opening being provided with at least one minute keyway, an elongated stem member symmetrically shaped with respect to said axial opening and tightly fitting therein and in surface contact with the entire extent of the wall of the strainer ele-' ment defining the axial opening exclusive of said keyway to provide a substantially impervious fit operating to substantially completely prevent the passage of fluid therebetween, said stem member providing stem portions extending from opposite sides of the strainer element and one of said stem portions having an outwardly projectin 'keymember registering with said keyway and passing" therethrough during assembly and disassembly ofthe strainer element and the stem member,- and an outward projection on the other stem portion spaced from said key member a distance slightly greater than the axial extent of said strainer element through the axial opening to permit limited relative sliding movement between the strainer element as an integral unit and the stem member to enable fluid to pass exteriorly around the strainer element while the fluid impervious fit be-- tween the strainer element and the stem member is maintained.

2. In a vacuum type infusion apparatus having interfitting upper and lower containers and av tubular passageway extending from the upper container into the lower contain-er and providing: a valve seat at the entrance end thereof, the pro-;

' 5 vision of a unitary filterin valve device in the form of a substantially spherical strainer element of unitary and integral construction having an outer roughened surface and a central axial opening therethrough, said axial opening being provided with a pair of minute keyways, an elongated stem member symmetrically shaped with respect to said axial opening and tightly fitting therein and in surface contact with the entire extent of the wall of the strainer element defining the axial opening between said keyways to provide a substantially impervious fit operating to substantially completely prevent the passage of fluid therebetween, said stem member providing stem portions extending from opposite sides of the strainer element and one of said stem portions having outwardly projecting key members spaced symmetrically with respect to the keyways in said axial opening registering therewith and passing therethrough during assembly and disassembly of the strainer element and the stem member, and an outward projection on the other stem portion spaced from said key members a distanceslightly greater than the axial extent of said strainer element through the axial opening to permit limited relative sliding movement between the strainer element as an integral unit and the stem member to enable fluid to pass exteriorly around the strainer element while the fluid impervious fit between the strainer element and the stem member 6 is maintained, the impervious fit between the strainer element and the stem member substantially preventing release of excess pressure developed in the lower container and thereby operating to effect separate upward movement of the stem member relative to the strainer element upon increase of vapor pressure in the lower container beyond a predetermined value to bring the said lower projection on the stem member into striking contact with the adjacent surface of the strainer element and to momentarily shift the strainer element from its associated valve seat on the upper container to relieve the excess pressure in the lower container.

CARL W. HELLBERG.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,927,287 Kell et a1 Sept. 19, 1933 2,058,136 Cory Oct. 20, 1936 2,291,427 Wolcott July 28, 1942 2,366,951 Aycock Jan. 9, 1945 2,376,410 Wolper May 22, 1945 2,387,322 Francis Oct. 23, 1945 2,390,269 Peterson Dec. 4, 1945 2,392,656 Foster. Jan. 8,1946 

